The present invention relates to a drive for floppy disks which is to be used as an auxiliary storage device in a computer, a word processor and the like, and more particularly, to improvements thereof.
A drive for floppy disks which is to be used as an auxiliary storage device in a computer, a word processor and the like comprises, as shown in FIG. 1, a shaft 2 connected to a rotary shaft of a motor and a rotating disk 1 fixed on the shaft 2 at the center thereof. The rotating disk 1 comprises a disk body 1A, an annular magnet 1B adhered to the surface of the disk body 1A, and a hub 3 provided at a center of the disk body. Further, the rotating disk 1 is formed with a concaved portion 4 which extends in the circumferential direction, and the concaved portion 4 is formed with an aperture 5 which is opened to the back of the rotating disk 1. Within the concaved portion 4 is received a plate 6 which extends in the circumferential direction of the rotating disk 1, and the plate 6 is swingably mounted on the rotating disk 1 at a base end portion 6b thereof by a pin 7. An engaging pin 8 is fixed to the other end of the plate 6 such as to project over the surface of the rotating disk 1, and a spring attachment piece 12 which penetrates through the aperture 5 so as to project from the back of the rotating disk 1 is provided at an intermediate portion of the plate 6. A spring attachment pin 13 is provided on the back of the rotating disk 1. A tension spring 14 or a torsion coil spring 15 is stretched between the spring attachment piece 12 and the spring attachment pin 13 (see FIGS. 2 and 4) so that the plate 6 is biased radially outwardly of the rotating disk 1 so as to be brought into contact with an inner wall portion 1a of the concaved portion 4. In consequence, the engaging pin 8 can be positioned at a fixed distance from the center of the rotating disk 1.
On the other hand, as shown in FIG. 6, a floppy disk has a hub 20 formed in the center thereof. The hub 20 is formed with a center hole 21 in the center thereof and an engaging hole 22 at a fixed distance from the center hole 21.
In case of loading the floppy disk, the hub surface of the floppy disk depresses the engaging pin 8 so that the plate 6 is deformed elastically to be pushed in the aperture 5 of the concaved portion 4 and, at the same time, the center hole 21 of the hub 20 of the floppy disk is brought into engagement with the shaft 2 of the rotating disk 1. Subsequently, the rotating disk 1 is rotated slowly as the engaging pin 8 is made to slide on the hub surface of the floppy disk. Then, the engaging pin 8 comes in the engaging hole 22 formed in the hub of the floppy disk so as to be engaged with a contact side n of the engaging hole 22 (see FIG. 7). The engaging pin 8 presses an outer side m away from the shaft 2 due to a component B of a reaction T which results when the engaging pin 8 presses on the contact side n of the engaging hole 22 and a spring force of the tension spring 14 or the torsion coil spring 15. In consequence, the shaft 2 is brought into contact with sides p and g of the center hole 21, so that the floppy disk is located in position (see FIG. 8). At the same time, the elastic restoring force of the plate 6 which acts to keep the hub 20 of the floppy disk apart from the rotating disk 1 can be cancelled. Then, the hub 20 of the floppy disk is magnetically attracted on the annular magnet 1B of the rotating disk 1 so that the engagement between the engaging pin 8 and the engaging hole 22 can be maintained.
In this condition, when the motor is driven, the rotation of the rotating disk 1 is transmitted to the floppy disk through the engaging pin 8, so that the floppy disk is made to rotate together with the rotating disk 1.
On the other hand, as shown in FIG. 6, the position of the outer side m of the engaging hole 22 formed in the hub 20 of the floppy disk with respect to the center hole 21 is defined by JIS and its dimensional tolerance is set relatively loosely. Further, since the pin 7 is located at a distance from the engaging pin 8 in the circumferential direction of the rotating disk 1, the engaging pin 8 is rotated counterclockwise about the pin 7. In this condition, assuming that an amount of dispersion in position of the outer side m of the engaging hole 22 formed in the hub 20 of the floppy disk is f (as shown in FIG. 7), since the engaging pin 8 is rotated counterclockwise about the pin 7, the standard position of the floppy disk is deviated by an angle 8 (see FIG. 8). As a result, the standard position of the floppy disk in the burst direction is varied greatly, resulting in the read error in some cases.
Further, the standard position in the burst direction is caused to be varied owing to the following reasons as well. As shown in FIG. 5, the base end portion 6b of the plate 6 loosely engages with a shaft portion 7b of the pin 7 and, in addition, a gap between a head portion 7a of the pin 7 and the rotating disk 1 is made larger than the thickness of the plate 6. For this reason, the base end portion 6b of the plate 6 cannot be made steady between the head portion 7a of the pin 7 and the rotating disk 1, so that the engaging pin 8 is fitted in the engaging hole 22 deeper or shallower than the position shown in FIG. 5 and it is not settled. More specifically, in the state where the engaging pin 8 is fitted in deeply as shown in FIG. 9, the engaging pin 8 is inclined toward the trailing side of the rotating direction of the rotating disk 1, so that its engaging position with the engaging hole 22 of the floppy disk deviates by +x from the position shown in FIG. 5, while in the state where the engaging pin 8 is fitted in shallower as shown in FIG. 10,,the engaging pin 8 is inclined toward the leading side of the rotating direction of the rotating disk 1, so that its engaging position with the engaging hole 22 of the floppy disk deviates by -x from the position shown in FIG. 5. In consequence, in this case as well, there arises a problem that the standard position of the floppy disk in burst direction is varied greatly when the floppy disk is rotated.
On the other hand, since there is mounted the tension spring 14 or the torsion coil spring 15 between the spring attachment piece 12 which penetrates through the aperture 5 of the rotating disk 1 so as to project from the back of the rotating disk 1 and the spring attachment pin 13 which is provided on the back of the rotating disk 1, it is necessary to provide a sufficiently large space adjacent to the back of the rotating disk 1 in order to prevent the spring from interfering with the motor. Therefore, the floppy disk drive is increased in size.
Accordingly, a first object of the present invention is to provide a floppy disk drive which is capable of minimizing the variation in standard position in the burst direction and occurrence of the read error.
A second object of the present invention is to provide a floppy disk drive the size of which is compact, particularly, the height of which is decreased.